ENANTIOSELECTIVE CATALYTIC INTRAMOLECULAR HYDROACYLATION

Catalysts of the type [ Rh(diphosphine)] (+) catalyze intramolecular c yclization of 4-pentenals to cyclopentanones. By using chiral diphosph ines, 4-substituted pentenals are converted to beta-substituted cyclop entanones with unusually high enantioselectivities. The mechanism of h ydroacylation is exceptionally complex and has been elucidated by deut erium labeling studies. It is shown that the enantioselection is contr olled by a series of intermediates and cannot be ascribed to a single step. (C) 1997 Elsevier Science S.A.